package sqlx

import (
        "bytes"
        "database/sql/driver"
        "errors"
        "reflect"
        "strconv"
        "strings"
        "sync"

        "github.com/muir/sqltoken"

        "github.com/vinovest/sqlx/reflectx"
)

// Bindvar types supported by Rebind, BindMap and BindStruct.
const (
        UNKNOWN = iota
        QUESTION
        DOLLAR
        NAMED
        AT
)

var defaultBinds = map[int][]string{
        DOLLAR:   {"postgres", "pgx", "pq-timeouts", "cloudsqlpostgres", "ql", "nrpostgres", "cockroach"},
        QUESTION: {"mysql", "sqlite3", "nrmysql", "nrsqlite3"},
        NAMED:    {"oci8", "ora", "goracle", "godror"},
        AT:       {"sqlserver", "azuresql"},
}

var binds sync.Map

var rebindConfigs = func() []sqltoken.Config {
        configs := make([]sqltoken.Config, AT+1)
        pg := sqltoken.PostgreSQLConfig()
        pg.NoticeQuestionMark = true
        pg.NoticeDollarNumber = false
        pg.SeparatePunctuation = true
        configs[DOLLAR] = pg

        ora := sqltoken.OracleConfig()
        ora.NoticeColonWord = false
        ora.NoticeQuestionMark = true
        ora.SeparatePunctuation = true
        configs[NAMED] = ora

        ssvr := sqltoken.SQLServerConfig()
        ssvr.NoticeAtWord = false
        ssvr.NoticeQuestionMark = true
        ssvr.SeparatePunctuation = true
        configs[AT] = ssvr
        return configs
}()

func init() {
        for bind, drivers := range defaultBinds {
                for _, driver := range drivers {
                        BindDriver(driver, bind)
                }
        }
}

// BindType returns the bindtype for a given database given a drivername.
func BindType(driverName string) int {
        itype, ok := binds.Load(driverName)
        if !ok {
                return UNKNOWN
        }
        return itype.(int)
}

// BindDriver sets the BindType for driverName to bindType.
func BindDriver(driverName string, bindType int) {
        binds.Store(driverName, bindType)
}

// Rebind a query from the default bindtype (QUESTION) to the target bindtype.
func Rebind(bindType int, query string) string {
        switch bindType {
        case QUESTION, UNKNOWN:
                return query
        }
        config := rebindConfigs[bindType]
        tokens := sqltoken.Tokenize(query, config)
        rqb := make([]byte, 0, len(query)+10)

        var j int
        for _, token := range tokens {
                if token.Type != sqltoken.QuestionMark {
                        rqb = append(rqb, ([]byte)(token.Text)...)
                        continue
                }
                switch bindType {
                case DOLLAR:
                        rqb = append(rqb, '$')
                case NAMED:
                        rqb = append(rqb, ':', 'a', 'r', 'g')
                case AT:
                        rqb = append(rqb, '@', 'p')
                }
                j++
                rqb = strconv.AppendInt(rqb, int64(j), 10)
        }
        return string(rqb)
}

// Experimental implementation of Rebind which uses a bytes.Buffer.  The code is
// much simpler and should be more resistant to odd unicode, but it is twice as
// slow.  Kept here for benchmarking purposes and to possibly replace Rebind if
// problems arise with its somewhat naive handling of unicode.
func rebindBuff(bindType int, query string) string {
        if bindType != DOLLAR {
                return query
        }

        b := make([]byte, 0, len(query))
        rqb := bytes.NewBuffer(b)
        j := 1
        for _, r := range query {
                if r == '?' {
                        rqb.WriteRune('$')
                        rqb.WriteString(strconv.Itoa(j))
                        j++
                } else {
                        rqb.WriteRune(r)
                }
        }

        return rqb.String()
}

func asSliceForIn(i interface{}) (v reflect.Value, ok bool) {
        if i == nil {
                return reflect.Value{}, false
        }

        v = reflect.ValueOf(i)
        t := reflectx.Deref(v.Type())

        // Only expand slices
        if t.Kind() != reflect.Slice {
                return reflect.Value{}, false
        }

        // []byte is a driver.Value type so it should not be expanded
        if t == reflect.TypeOf([]byte{}) {
                return reflect.Value{}, false
        }

        return v, true
}

// In expands slice values in args, returning the modified query string
// and a new arg list that can be executed by a database. The `query` should
// use the `?` bindVar.  The return value uses the `?` bindVar.
func In(query string, args ...interface{}) (string, []interface{}, error) {
        // argMeta stores reflect.Value and length for slices and
        // the value itself for non-slice arguments
        type argMeta struct {
                v      reflect.Value
                i      interface{}
                length int
        }

        var flatArgsCount int
        var anySlices bool

        var stackMeta [32]argMeta

        var meta []argMeta
        if len(args) <= len(stackMeta) {
                meta = stackMeta[:len(args)]
        } else {
                meta = make([]argMeta, len(args))
        }

        for i, arg := range args {
                if a, ok := arg.(driver.Valuer); ok {
                        var err error
                        arg, err = callValuerValue(a)
                        if err != nil {
                                return "", nil, err
                        }
                }

                if v, ok := asSliceForIn(arg); ok {
                        meta[i].length = v.Len()
                        meta[i].v = v

                        anySlices = true
                        flatArgsCount += meta[i].length

                        if meta[i].length == 0 {
                                return "", nil, errors.New("empty slice passed to 'in' query")
                        }
                } else {
                        meta[i].i = arg
                        flatArgsCount++
                }
        }

        // don't do any parsing if there aren't any slices;  note that this means
        // some errors that we might have caught below will not be returned.
        if !anySlices {
                return query, args, nil
        }

        newArgs := make([]interface{}, 0, flatArgsCount)

        var buf strings.Builder
        buf.Grow(len(query) + len(", ?")*flatArgsCount)

        var arg, offset int

        for i := strings.IndexByte(query[offset:], '?'); i != -1; i = strings.IndexByte(query[offset:], '?') {
                if arg >= len(meta) {
                        // if an argument wasn't passed, lets return an error;  this is
                        // not actually how database/sql Exec/Query works, but since we are
                        // creating an argument list programmatically, we want to be able
                        // to catch these programmer errors earlier.
                        return "", nil, errors.New("number of bindVars exceeds arguments")
                }

                argMeta := meta[arg]
                arg++

                // not a slice, continue.
                // our questionmark will either be written before the next expansion
                // of a slice or after the loop when writing the rest of the query
                if argMeta.length == 0 {
                        offset = offset + i + 1
                        newArgs = append(newArgs, argMeta.i)
                        continue
                }

                // write everything up to and including our ? character
                buf.WriteString(query[:offset+i+1])

                for si := 1; si < argMeta.length; si++ {
                        buf.WriteString(", ?")
                }

                newArgs = appendReflectSlice(newArgs, argMeta.v, argMeta.length)

                // slice the query and reset the offset. this avoids some bookkeeping for
                // the write after the loop
                query = query[offset+i+1:]
                offset = 0
        }

        buf.WriteString(query)

        if arg < len(meta) {
                return "", nil, errors.New("number of bindVars less than number arguments")
        }

        return buf.String(), newArgs, nil
}

func appendReflectSlice(args []interface{}, v reflect.Value, vlen int) []interface{} {
        switch val := v.Interface().(type) {
        case []interface{}:
                args = append(args, val...)
        case []int:
                for i := range val {
                        args = append(args, val[i])
                }
        case []string:
                for i := range val {
                        args = append(args, val[i])
                }
        default:
                for si := 0; si < vlen; si++ {
                        args = append(args, v.Index(si).Interface())
                }
        }

        return args
}

// callValuerValue returns vr.Value(), with one exception:
// If vr.Value is an auto-generated method on a pointer type and the
// pointer is nil, it would panic at runtime in the panicwrap
// method. Treat it like nil instead.
// Issue 8415.
//
// This is so people can implement driver.Value on value types and
// still use nil pointers to those types to mean nil/NULL, just like
// string/*string.
//
// This function is copied from database/sql/driver package
// and mirrored in the database/sql package.
func callValuerValue(vr driver.Valuer) (v driver.Value, err error) {
        if rv := reflect.ValueOf(vr); rv.Kind() == reflect.Pointer &&
                rv.IsNil() &&
                rv.Type().Elem().Implements(reflect.TypeOf((*driver.Valuer)(nil)).Elem()) {
                return nil, nil
        }
        return vr.Value()
}

package sqlx

// Named Query Support
//
//  * BindMap - bind query bindvars to map/struct args
//        * NamedExec, NamedQuery - named query w/ struct or map
//  * NamedStmt - a pre-compiled named query which is a prepared statement
//
// Internal Interfaces:
//
//  * compileNamedQuery - rebind a named query, returning a query and list of names
//  * bindArgs, bindMapArgs, bindAnyArgs - given a list of names, return an arglist
//
import (
        "bytes"
        "database/sql"
        "fmt"
        "reflect"
        "strconv"
        "strings"

        "github.com/muir/sqltoken"

        "github.com/vinovest/sqlx/reflectx"
)

// NamedStmt is a prepared statement that executes named queries.  Prepare it
// how you would execute a NamedQuery, but pass in a struct or map when executing.
type NamedStmt struct {
        Params      []string
        QueryString string
        Stmt        *Stmt
}

// Close closes the named statement.
func (n *NamedStmt) Close() error {
        return n.Stmt.Close()
}

// Exec executes a named statement using the struct passed.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) Exec(arg interface{}) (sql.Result, error) {
        args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
        if err != nil {
                return *new(sql.Result), err
        }
        return n.Stmt.Exec(args...)
}

// Query executes a named statement using the struct argument, returning rows.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) Query(arg interface{}) (*sql.Rows, error) {
        args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
        if err != nil {
                return nil, err
        }
        return n.Stmt.Query(args...)
}

// QueryRow executes a named statement against the database.  Because sqlx cannot
// create a *sql.Row with an error condition pre-set for binding errors, sqlx
// returns a *sqlx.Row instead.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) QueryRow(arg interface{}) *Row {
        args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
        if err != nil {
                return &Row{err: err}
        }
        return n.Stmt.QueryRowx(args...)
}

// MustExec execs a NamedStmt, panicing on error
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) MustExec(arg interface{}) sql.Result {
        res, err := n.Exec(arg)
        if err != nil {
                panic(err)
        }
        return res
}

// Queryx using this NamedStmt
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) Queryx(arg interface{}) (*Rows, error) {
        r, err := n.Query(arg)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, Mapper: n.Stmt.Mapper, unsafe: isUnsafe(n)}, err
}

// QueryRowx this NamedStmt.  Because of limitations with QueryRow, this is
// an alias for QueryRow.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) QueryRowx(arg interface{}) *Row {
        return n.QueryRow(arg)
}

// Select using this NamedStmt
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) Select(dest interface{}, arg interface{}) error {
        rows, err := n.Queryx(arg)
        if err != nil {
                return err
        }
        // if something happens here, we want to make sure the rows are Closed
        defer rows.Close()
        return scanAll(rows, dest, false)
}

// Get using this NamedStmt
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) Get(dest interface{}, arg interface{}) error {
        r := n.QueryRowx(arg)
        return r.scanAny(dest, false)
}

// Unsafe creates an unsafe version of the NamedStmt
func (n *NamedStmt) Unsafe() *NamedStmt {
        r := &NamedStmt{Params: n.Params, Stmt: n.Stmt, QueryString: n.QueryString}
        r.Stmt.unsafe = true
        return r
}

// A union interface of preparer and binder, required to be able to prepare
// named statements (as the bindtype must be determined).
type namedPreparer interface {
        Preparer
        binder
}

func prepareNamed(p namedPreparer, query string) (*NamedStmt, error) {
        bindType := BindType(p.DriverName())
        compiled, err := compileNamedQuery([]byte(query), bindType)
        if err != nil {
                return nil, err
        }
        stmt, err := Preparex(p, compiled.query)
        if err != nil {
                return nil, err
        }
        return &NamedStmt{
                QueryString: compiled.query,
                Params:      compiled.names,
                Stmt:        stmt,
        }, nil
}

// convertMapStringInterface attempts to convert v to map[string]interface{}.
// Unlike v.(map[string]interface{}), this function works on named types that
// are convertible to map[string]interface{} as well.
func convertMapStringInterface(v interface{}) (map[string]interface{}, bool) {
        var m map[string]interface{}
        mtype := reflect.TypeOf(m)
        t := reflect.TypeOf(v)
        if !t.ConvertibleTo(mtype) {
                return nil, false
        }
        return reflect.ValueOf(v).Convert(mtype).Interface().(map[string]interface{}), true
}

func bindAnyArgs(names []string, arg interface{}, m *reflectx.Mapper) ([]interface{}, error) {
        if maparg, ok := convertMapStringInterface(arg); ok {
                return bindMapArgs(names, maparg)
        }
        return bindArgs(names, arg, m)
}

// private interface to generate a list of interfaces from a given struct
// type, given a list of names to pull out of the struct.  Used by public
// BindStruct interface.
func bindArgs(names []string, arg interface{}, m *reflectx.Mapper) ([]interface{}, error) {
        arglist := make([]interface{}, 0, len(names))

        // grab the indirected value of arg
        var v reflect.Value
        for v = reflect.ValueOf(arg); v.Kind() == reflect.Ptr; {
                v = v.Elem()
        }

        err := m.TraversalsByNameFunc(v.Type(), names, func(i int, t []int) error {
                if len(t) == 0 {
                        return fmt.Errorf("could not find name %s in %#v", names[i], arg)
                }

                val := reflectx.FieldByIndexesReadOnly(v, t)
                arglist = append(arglist, val.Interface())

                return nil
        })

        return arglist, err
}

// like bindArgs, but for maps.
func bindMapArgs(names []string, arg map[string]interface{}) ([]interface{}, error) {
        arglist := make([]interface{}, 0, len(names))

        for _, name := range names {
                val, ok := arg[name]
                if !ok {
                        return arglist, fmt.Errorf("could not find name %s in %#v", name, arg)
                }
                arglist = append(arglist, val)
        }
        return arglist, nil
}

// bindStruct binds a named parameter query with fields from a struct argument.
// The rules for binding field names to parameter names follow the same
// conventions as for StructScan, including obeying the `db` struct tags.
func bindStruct(bindType int, query string, arg interface{}, m *reflectx.Mapper) (string, []interface{}, error) {
        compiled, err := compileNamedQuery([]byte(query), bindType)
        if err != nil {
                return "", []interface{}{}, err
        }

        arglist, err := bindAnyArgs(compiled.names, arg, m)
        if err != nil {
                return "", []interface{}{}, err
        }

        return compiled.query, arglist, nil
}

func fixBound(cq *compiledQueryResult, loop int) {
        if cq.valuesStart == nil || cq.valuesEnd == nil {
                return
        }
        buffer := bytes.NewBuffer(make([]byte, 0, (int(*cq.valuesEnd-1)-int(*cq.valuesStart))*loop+
                // bytes for commas, too
                (loop-1)+
                // plus the query
                (len(cq.query)-int(*cq.valuesEnd)+int(*cq.valuesStart))))

        buffer.WriteString(cq.query[0:*cq.valuesEnd])
        for i := 0; i < loop-1; i++ {
                buffer.WriteString(",")
                buffer.WriteString(cq.query[*cq.valuesStart:*cq.valuesEnd])
        }
        buffer.WriteString(cq.query[*cq.valuesEnd:])
        cq.query = buffer.String()
}

// bindArray binds a named parameter query with fields from an array or slice of
// structs argument.
func bindArray(bindType int, query string, arg interface{}, m *reflectx.Mapper) (string, []interface{}, error) {
        // do the initial binding with QUESTION;  if bindType is not question,
        // we can rebind it at the end.
        compiled, err := compileNamedQuery([]byte(query), QUESTION)
        if err != nil {
                return "", []interface{}{}, err
        }
        arrayValue := reflect.ValueOf(arg)
        arrayLen := arrayValue.Len()
        if arrayLen == 0 {
                return "", []interface{}{}, fmt.Errorf("length of array is 0: %#v", arg)
        }
        arglist := make([]interface{}, 0, len(compiled.names)*arrayLen)
        for i := 0; i < arrayLen; i++ {
                elemArglist, err := bindAnyArgs(compiled.names, arrayValue.Index(i).Interface(), m)
                if err != nil {
                        return "", []interface{}{}, err
                }
                arglist = append(arglist, elemArglist...)
        }
        if arrayLen > 1 {
                fixBound(&compiled, arrayLen)
        }
        // adjust binding type if we weren't on question
        bound := compiled.query
        if bindType != QUESTION {
                bound = Rebind(bindType, bound)
        }
        return bound, arglist, nil
}

// bindMap binds a named parameter query with a map of arguments.
func bindMap(bindType int, query string, args map[string]interface{}) (string, []interface{}, error) {
        compiled, err := compileNamedQuery([]byte(query), bindType)
        if err != nil {
                return "", []interface{}{}, err
        }

        arglist, err := bindMapArgs(compiled.names, args)
        return compiled.query, arglist, err
}

var namedParseConfigs = func() []sqltoken.Config {
        configs := make([]sqltoken.Config, AT+1)
        pg := sqltoken.PostgreSQLConfig()
        pg.NoticeColonWord = true
        pg.ColonWordIncludesUnicode = true
        pg.NoticeDollarNumber = false
        pg.NoticeQuestionMark = true
        pg.SeparatePunctuation = true
        configs[DOLLAR] = pg

        ora := sqltoken.OracleConfig()
        ora.ColonWordIncludesUnicode = true
        ora.NoticeQuestionMark = true
        ora.SeparatePunctuation = true
        configs[NAMED] = ora

        ssvr := sqltoken.SQLServerConfig()
        ssvr.NoticeColonWord = true
        ssvr.ColonWordIncludesUnicode = true
        ssvr.NoticeAtWord = false
        ssvr.SeparatePunctuation = true
        configs[AT] = ssvr

        mysql := sqltoken.MySQLConfig()
        mysql.NoticeColonWord = true
        mysql.ColonWordIncludesUnicode = true
        mysql.NoticeQuestionMark = true
        mysql.SeparatePunctuation = true
        configs[QUESTION] = mysql
        configs[UNKNOWN] = mysql
        return configs
}()

// -- Compilation of Named Queries

// FIXME: this function isn't safe for unicode named params, as a failing test
// can testify.  This is not a regression but a failure of the original code
// as well.  It should be modified to range over runes in a string rather than
// bytes, even though this is less convenient and slower.  Hopefully the
// addition of the prepared NamedStmt (which will only do this once) will make
// up for the slightly slower ad-hoc NamedExec/NamedQuery.

type compiledQueryResult struct {
        // the query string with the named parameters swapped out with bindvars
        query string

        // the name of the parameter
        names []string

        // if set, the start position of the VALUES argument list not including () (end inclusive)
        valuesStart *uint32
        valuesEnd   *uint32
}

// compile a NamedQuery into an unbound query (using the '?' bindvar) and
// a list of names.
func compileNamedQuery(qs []byte, bindType int) (compiledQueryResult, error) {
        r := compiledQueryResult{
                names: make([]string, 0, 10),
        }
        curpos := uint32(0)
        rebound := make([]byte, 0, len(qs))
        inValues := false
        inValuesOpenCount := 0

        currentVar := 1
        tokens := sqltoken.Tokenize(string(qs), namedParseConfigs[bindType])

        for _, token := range tokens {
                if token.Type == sqltoken.Word && strings.EqualFold("values", token.Text) && !inValues {
                        // current behavior: expand the first values and ignore the rest
                        if r.valuesStart == nil { // did we already parse a values statement?
                                inValues = true
                        }
                }
                if inValues && token.Type == sqltoken.Punctuation {
                        if token.Text == "(" {
                                start := curpos
                                inValuesOpenCount += 1
                                if r.valuesStart == nil {
                                        r.valuesStart = &start
                                }
                        }
                        if token.Text == ")" {
                                inValuesOpenCount -= 1
                                if inValuesOpenCount == 0 {
                                        end := curpos + 1
                                        r.valuesEnd = &end
                                        inValues = false
                                }
                        }
                }
                if token.Type != sqltoken.ColonWord {
                        rebound = append(rebound, ([]byte)(token.Text)...)
                        curpos += uint32(len(token.Text))
                        continue
                }
                r.names = append(r.names, token.Text[1:])

                newBound := ""
                switch bindType {
                // oracle only supports named type bind vars even for positional
                case NAMED:
                        newBound = token.Text
                case QUESTION, UNKNOWN:
                        newBound = "?"
                case DOLLAR:
                        newBound = "$" + strconv.Itoa(currentVar)
                        currentVar++
                case AT:
                        newBound = "@p" + strconv.Itoa(currentVar)
                        currentVar++
                }

                rebound = append(rebound, []byte(newBound)...)
                curpos += uint32(len(newBound))
        }

        if inValues {
                return r, fmt.Errorf("missing closing bracket in VALUES")
        }
        r.query = string(rebound)
        return r, nil
}

// BindNamed binds a struct or a map to a query with named parameters.
// DEPRECATED: use sqlx.Named` instead of this, it may be removed in future.
func BindNamed(bindType int, query string, arg interface{}) (string, []interface{}, error) {
        return bindNamedMapper(bindType, query, arg, mapper())
}

// Named takes a query using named parameters and an argument and
// returns a new query with a list of args that can be executed by
// a database.  The return value uses the `?` bindvar.
func Named(query string, arg interface{}) (string, []interface{}, error) {
        return bindNamedMapper(QUESTION, query, arg, mapper())
}

func bindNamedMapper(bindType int, query string, arg interface{}, m *reflectx.Mapper) (string, []interface{}, error) {
        t := reflect.TypeOf(arg)
        k := t.Kind()
        switch {
        case k == reflect.Map && t.Key().Kind() == reflect.String:
                m, ok := convertMapStringInterface(arg)
                if !ok {
                        return "", nil, fmt.Errorf("sqlx.bindNamedMapper: unsupported map type: %T", arg)
                }
                return bindMap(bindType, query, m)
        case k == reflect.Array || k == reflect.Slice:
                return bindArray(bindType, query, arg, m)
        default:
                return bindStruct(bindType, query, arg, m)
        }
}

// NamedQuery binds a named query and then runs Query on the result using the
// provided Ext (sqlx.Tx, sqlx.Db).  It works with both structs and with
// map[string]interface{} types.
func NamedQuery(e Ext, query string, arg interface{}) (*Rows, error) {
        q, args, err := bindNamedMapper(BindType(e.DriverName()), query, arg, mapperFor(e))
        if err != nil {
                return nil, err
        }
        return e.Queryx(q, args...)
}

// NamedExec uses BindStruct to get a query executable by the driver and
// then runs Exec on the result.  Returns an error from the binding
// or the query execution itself.
func NamedExec(e Ext, query string, arg interface{}) (sql.Result, error) {
        q, args, err := bindNamedMapper(BindType(e.DriverName()), query, arg, mapperFor(e))
        if err != nil {
                return nil, err
        }
        return e.Exec(q, args...)
}

package sqlx

import (
        "context"
        "database/sql"
)

// A union interface of contextPreparer and binder, required to be able to
// prepare named statements with context (as the bindtype must be determined).
type namedPreparerContext interface {
        PreparerContext
        binder
}

func prepareNamedContext(ctx context.Context, p namedPreparerContext, query string) (*NamedStmt, error) {
        bindType := BindType(p.DriverName())
        compiled, err := compileNamedQuery([]byte(query), bindType)
        if err != nil {
                return nil, err
        }
        stmt, err := PreparexContext(ctx, p, compiled.query)
        if err != nil {
                return nil, err
        }
        return &NamedStmt{
                QueryString: compiled.query,
                Params:      compiled.names,
                Stmt:        stmt,
        }, nil
}

// ExecContext executes a named statement using the struct passed.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) ExecContext(ctx context.Context, arg interface{}) (sql.Result, error) {
        args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
        if err != nil {
                return *new(sql.Result), err
        }
        return n.Stmt.ExecContext(ctx, args...)
}

// QueryContext executes a named statement using the struct argument, returning rows.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) QueryContext(ctx context.Context, arg interface{}) (*sql.Rows, error) {
        args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
        if err != nil {
                return nil, err
        }
        return n.Stmt.QueryContext(ctx, args...)
}

// QueryRowContext executes a named statement against the database.  Because sqlx cannot
// create a *sql.Row with an error condition pre-set for binding errors, sqlx
// returns a *sqlx.Row instead.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) QueryRowContext(ctx context.Context, arg interface{}) *Row {
        args, err := bindAnyArgs(n.Params, arg, n.Stmt.Mapper)
        if err != nil {
                return &Row{err: err}
        }
        return n.Stmt.QueryRowxContext(ctx, args...)
}

// MustExecContext execs a NamedStmt, panicing on error
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) MustExecContext(ctx context.Context, arg interface{}) sql.Result {
        res, err := n.ExecContext(ctx, arg)
        if err != nil {
                panic(err)
        }
        return res
}

// QueryxContext using this NamedStmt
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) QueryxContext(ctx context.Context, arg interface{}) (*Rows, error) {
        r, err := n.QueryContext(ctx, arg)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, Mapper: n.Stmt.Mapper, unsafe: isUnsafe(n)}, err
}

// QueryRowxContext this NamedStmt.  Because of limitations with QueryRow, this is
// an alias for QueryRow.
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) QueryRowxContext(ctx context.Context, arg interface{}) *Row {
        return n.QueryRowContext(ctx, arg)
}

// SelectContext using this NamedStmt
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) SelectContext(ctx context.Context, dest interface{}, arg interface{}) error {
        rows, err := n.QueryxContext(ctx, arg)
        if err != nil {
                return err
        }
        // if something happens here, we want to make sure the rows are Closed
        defer rows.Close()
        return scanAll(rows, dest, false)
}

// GetContext using this NamedStmt
// Any named placeholder parameters are replaced with fields from arg.
func (n *NamedStmt) GetContext(ctx context.Context, dest interface{}, arg interface{}) error {
        r := n.QueryRowxContext(ctx, arg)
        return r.scanAny(dest, false)
}

// NamedQueryContext binds a named query and then runs Query on the result using the
// provided Ext (sqlx.Tx, sqlx.Db).  It works with both structs and with
// map[string]interface{} types.
func NamedQueryContext(ctx context.Context, e ExtContext, query string, arg interface{}) (*Rows, error) {
        q, args, err := bindNamedMapper(BindType(e.DriverName()), query, arg, mapperFor(e))
        if err != nil {
                return nil, err
        }
        return e.QueryxContext(ctx, q, args...)
}

// NamedExecContext uses BindStruct to get a query executable by the driver and
// then runs Exec on the result.  Returns an error from the binding
// or the query execution itself.
func NamedExecContext(ctx context.Context, e ExtContext, query string, arg interface{}) (sql.Result, error) {
        q, args, err := bindNamedMapper(BindType(e.DriverName()), query, arg, mapperFor(e))
        if err != nil {
                return nil, err
        }
        return e.ExecContext(ctx, q, args...)
}

// Package reflectx implements extensions to the standard reflect lib suitable
// for implementing marshalling and unmarshalling packages.  The main Mapper type
// allows for Go-compatible named attribute access, including accessing embedded
// struct attributes and the ability to use  functions and struct tags to
// customize field names.
package reflectx

import (
        "reflect"
        "runtime"
        "strings"
        "sync"
)

// A FieldInfo is metadata for a struct field.
type FieldInfo struct {
        Index    []int
        Path     string
        Field    reflect.StructField
        Zero     reflect.Value
        Name     string
        Options  map[string]string
        Embedded bool
        Children []*FieldInfo
        Parent   *FieldInfo
}

// A StructMap is an index of field metadata for a struct.
type StructMap struct {
        Tree  *FieldInfo
        Index []*FieldInfo
        Paths map[string]*FieldInfo
        Names map[string]*FieldInfo
}

// GetByPath returns a *FieldInfo for a given string path.
func (f StructMap) GetByPath(path string) *FieldInfo {
        return f.Paths[path]
}

// GetByTraversal returns a *FieldInfo for a given integer path.  It is
// analogous to reflect.FieldByIndex, but using the cached traversal
// rather than re-executing the reflect machinery each time.
func (f StructMap) GetByTraversal(index []int) *FieldInfo {
        if len(index) == 0 {
                return nil
        }

        tree := f.Tree
        for _, i := range index {
                if i >= len(tree.Children) || tree.Children[i] == nil {
                        return nil
                }
                tree = tree.Children[i]
        }
        return tree
}

// Mapper is a general purpose mapper of names to struct fields.  A Mapper
// behaves like most marshallers in the standard library, obeying a field tag
// for name mapping but also providing a basic transform function.
type Mapper struct {
        cache      map[reflect.Type]*StructMap
        tagName    string
        tagMapFunc func(string) string
        mapFunc    func(string) string
        mutex      sync.Mutex
}

// NewMapper returns a new mapper using the tagName as its struct field tag.
// If tagName is the empty string, it is ignored.
func NewMapper(tagName string) *Mapper {
        return &Mapper{
                cache:   make(map[reflect.Type]*StructMap),
                tagName: tagName,
        }
}

// NewMapperTagFunc returns a new mapper which contains a mapper for field names
// AND a mapper for tag values.  This is useful for tags like json which can
// have values like "name,omitempty".
func NewMapperTagFunc(tagName string, mapFunc, tagMapFunc func(string) string) *Mapper {
        return &Mapper{
                cache:      make(map[reflect.Type]*StructMap),
                tagName:    tagName,
                mapFunc:    mapFunc,
                tagMapFunc: tagMapFunc,
        }
}

// NewMapperFunc returns a new mapper which optionally obeys a field tag and
// a struct field name mapper func given by f.  Tags will take precedence, but
// for any other field, the mapped name will be f(field.Name)
func NewMapperFunc(tagName string, f func(string) string) *Mapper {
        return &Mapper{
                cache:   make(map[reflect.Type]*StructMap),
                tagName: tagName,
                mapFunc: f,
        }
}

// TypeMap returns a mapping of field strings to int slices representing
// the traversal down the struct to reach the field.
func (m *Mapper) TypeMap(t reflect.Type) *StructMap {
        m.mutex.Lock()
        mapping, ok := m.cache[t]
        if !ok {
                mapping = getMapping(t, m.tagName, m.mapFunc, m.tagMapFunc)
                m.cache[t] = mapping
        }
        m.mutex.Unlock()
        return mapping
}

// FieldMap returns the mapper's mapping of field names to reflect values.  Panics
// if v's Kind is not Struct, or v is not Indirectable to a struct kind.
func (m *Mapper) FieldMap(v reflect.Value) map[string]reflect.Value {
        v = reflect.Indirect(v)
        mustBe(v, reflect.Struct)

        r := map[string]reflect.Value{}
        tm := m.TypeMap(v.Type())
        for tagName, fi := range tm.Names {
                r[tagName] = FieldByIndexes(v, fi.Index)
        }
        return r
}

// FieldByName returns a field by its mapped name as a reflect.Value.
// Panics if v's Kind is not Struct or v is not Indirectable to a struct Kind.
// Returns zero Value if the name is not found.
func (m *Mapper) FieldByName(v reflect.Value, name string) reflect.Value {
        v = reflect.Indirect(v)
        mustBe(v, reflect.Struct)

        tm := m.TypeMap(v.Type())
        fi, ok := tm.Names[name]
        if !ok {
                return v
        }
        return FieldByIndexes(v, fi.Index)
}

// FieldsByName returns a slice of values corresponding to the slice of names
// for the value.  Panics if v's Kind is not Struct or v is not Indirectable
// to a struct Kind.  Returns zero Value for each name not found.
func (m *Mapper) FieldsByName(v reflect.Value, names []string) []reflect.Value {
        v = reflect.Indirect(v)
        mustBe(v, reflect.Struct)

        tm := m.TypeMap(v.Type())
        vals := make([]reflect.Value, 0, len(names))
        for _, name := range names {
                fi, ok := tm.Names[name]
                if !ok {
                        vals = append(vals, *new(reflect.Value))
                } else {
                        vals = append(vals, FieldByIndexes(v, fi.Index))
                }
        }
        return vals
}

// TraversalsByName returns a slice of int slices which represent the struct
// traversals for each mapped name.  Panics if t is not a struct or Indirectable
// to a struct.  Returns empty int slice for each name not found.
func (m *Mapper) TraversalsByName(t reflect.Type, names []string) [][]int {
        r := make([][]int, 0, len(names))
        m.TraversalsByNameFunc(t, names, func(_ int, i []int) error {
                if i == nil {
                        r = append(r, []int{})
                } else {
                        r = append(r, i)
                }

                return nil
        })
        return r
}

// TraversalsByNameFunc traverses the mapped names and calls fn with the index of
// each name and the struct traversal represented by that name. Panics if t is not
// a struct or Indirectable to a struct. Returns the first error returned by fn or nil.
func (m *Mapper) TraversalsByNameFunc(t reflect.Type, names []string, fn func(int, []int) error) error {
        t = Deref(t)
        mustBe(t, reflect.Struct)
        tm := m.TypeMap(t)
        for i, name := range names {
                fi, ok := tm.Names[name]
                if !ok {
                        if err := fn(i, nil); err != nil {
                                return err
                        }
                } else {
                        if err := fn(i, fi.Index); err != nil {
                                return err
                        }
                }
        }
        return nil
}

// FieldByIndexes returns a value for the field given by the struct traversal
// for the given value.
func FieldByIndexes(v reflect.Value, indexes []int) reflect.Value {
        for _, i := range indexes {
                v = reflect.Indirect(v).Field(i)
                // if this is a pointer and it's nil, allocate a new value and set it
                if v.Kind() == reflect.Ptr && v.IsNil() {
                        alloc := reflect.New(Deref(v.Type()))
                        v.Set(alloc)
                }
                if v.Kind() == reflect.Map && v.IsNil() {
                        v.Set(reflect.MakeMap(v.Type()))
                }
        }
        return v
}

// FieldByIndexesReadOnly returns a value for a particular struct traversal,
// but is not concerned with allocating nil pointers because the value is
// going to be used for reading and not setting.
func FieldByIndexesReadOnly(v reflect.Value, indexes []int) reflect.Value {
        for _, i := range indexes {
                v = reflect.Indirect(v).Field(i)
        }
        return v
}

// Deref is Indirect for reflect.Types
func Deref(t reflect.Type) reflect.Type {
        if t.Kind() == reflect.Ptr {
                t = t.Elem()
        }
        return t
}

// -- helpers & utilities --

type kinder interface {
        Kind() reflect.Kind
}

// mustBe checks a value against a kind, panicing with a reflect.ValueError
// if the kind isn't that which is required.
func mustBe(v kinder, expected reflect.Kind) {
        if k := v.Kind(); k != expected {
                panic(&reflect.ValueError{Method: methodName(), Kind: k})
        }
}

// methodName returns the caller of the function calling methodName
func methodName() string {
        pc, _, _, _ := runtime.Caller(2)
        f := runtime.FuncForPC(pc)
        if f == nil {
                return "unknown method"
        }
        return f.Name()
}

type typeQueue struct {
        t  reflect.Type
        fi *FieldInfo
        pp string // Parent path
}

// A copying append that creates a new slice each time.
func apnd(is []int, i int) []int {
        x := make([]int, len(is)+1)
        copy(x, is)
        x[len(x)-1] = i
        return x
}

type mapf func(string) string

// parseName parses the tag and the target name for the given field using
// the tagName (eg 'json' for `json:"foo"` tags), mapFunc for mapping the
// field's name to a target name, and tagMapFunc for mapping the tag to
// a target name.
func parseName(field reflect.StructField, tagName string, mapFunc, tagMapFunc mapf) (tag, fieldName string) {
        // first, set the fieldName to the field's name
        fieldName = field.Name
        // if a mapFunc is set, use that to override the fieldName
        if mapFunc != nil {
                fieldName = mapFunc(fieldName)
        }

        // if there's no tag to look for, return the field name
        if tagName == "" {
                return "", fieldName
        }

        // if this tag is not set using the normal convention in the tag,
        // then return the fieldname..  this check is done because according
        // to the reflect documentation:
        //    If the tag does not have the conventional format,
        //    the value returned by Get is unspecified.
        // which doesn't sound great.
        if !strings.Contains(string(field.Tag), tagName+":") {
                return "", fieldName
        }

        // at this point we're fairly sure that we have a tag, so lets pull it out
        tag = field.Tag.Get(tagName)

        // if we have a mapper function, call it on the whole tag
        // XXX: this is a change from the old version, which pulled out the name
        // before the tagMapFunc could be run, but I think this is the right way
        if tagMapFunc != nil {
                tag = tagMapFunc(tag)
        }

        // finally, split the options from the name
        parts := strings.Split(tag, ",")
        fieldName = parts[0]

        return tag, fieldName
}

// parseOptions parses options out of a tag string, skipping the name
func parseOptions(tag string) map[string]string {
        parts := strings.Split(tag, ",")
        options := make(map[string]string, len(parts))
        if len(parts) > 1 {
                for _, opt := range parts[1:] {
                        // short circuit potentially expensive split op
                        if strings.Contains(opt, "=") {
                                kv := strings.Split(opt, "=")
                                options[kv[0]] = kv[1]
                                continue
                        }
                        options[opt] = ""
                }
        }
        return options
}

// getMapping returns a mapping for the t type, using the tagName, mapFunc and
// tagMapFunc to determine the canonical names of fields.
func getMapping(t reflect.Type, tagName string, mapFunc, tagMapFunc mapf) *StructMap {
        m := []*FieldInfo{}

        root := &FieldInfo{}
        queue := []typeQueue{}
        queue = append(queue, typeQueue{Deref(t), root, ""})

QueueLoop:
        for len(queue) != 0 {
                // pop the first item off of the queue
                tq := queue[0]
                queue = queue[1:]

                // ignore recursive field
                for p := tq.fi.Parent; p != nil; p = p.Parent {
                        if tq.fi.Field.Type == p.Field.Type {
                                continue QueueLoop
                        }
                }

                nChildren := 0
                if tq.t.Kind() == reflect.Struct {
                        nChildren = tq.t.NumField()
                }
                tq.fi.Children = make([]*FieldInfo, nChildren)

                // iterate through all of its fields
                for fieldPos := 0; fieldPos < nChildren; fieldPos++ {

                        f := tq.t.Field(fieldPos)

                        // parse the tag and the target name using the mapping options for this field
                        tag, name := parseName(f, tagName, mapFunc, tagMapFunc)

                        // if the name is "-", disabled via a tag, skip it
                        if name == "-" {
                                continue
                        }

                        fi := FieldInfo{
                                Field:   f,
                                Name:    name,
                                Zero:    reflect.New(f.Type).Elem(),
                                Options: parseOptions(tag),
                        }

                        // if the path is empty this path is just the name
                        if tq.pp == "" {
                                fi.Path = fi.Name
                        } else {
                                fi.Path = tq.pp + "." + fi.Name
                        }

                        // skip unexported fields
                        if len(f.PkgPath) != 0 && !f.Anonymous {
                                continue
                        }

                        // bfs search of anonymous embedded structs
                        if f.Anonymous {
                                pp := tq.pp
                                if tag != "" {
                                        pp = fi.Path
                                }

                                fi.Embedded = true
                                fi.Index = apnd(tq.fi.Index, fieldPos)
                                nChildren := 0
                                ft := Deref(f.Type)
                                if ft.Kind() == reflect.Struct {
                                        nChildren = ft.NumField()
                                }
                                fi.Children = make([]*FieldInfo, nChildren)
                                queue = append(queue, typeQueue{Deref(f.Type), &fi, pp})
                        } else if fi.Zero.Kind() == reflect.Struct || (fi.Zero.Kind() == reflect.Ptr && fi.Zero.Type().Elem().Kind() == reflect.Struct) {
                                fi.Index = apnd(tq.fi.Index, fieldPos)
                                fi.Children = make([]*FieldInfo, Deref(f.Type).NumField())
                                queue = append(queue, typeQueue{Deref(f.Type), &fi, fi.Path})
                        }

                        fi.Index = apnd(tq.fi.Index, fieldPos)
                        fi.Parent = tq.fi
                        tq.fi.Children[fieldPos] = &fi
                        m = append(m, &fi)
                }
        }

        flds := &StructMap{Index: m, Tree: root, Paths: map[string]*FieldInfo{}, Names: map[string]*FieldInfo{}}
        for _, fi := range flds.Index {
                // check if nothing has already been pushed with the same path
                // sometimes you can choose to override a type using embedded struct
                fld, ok := flds.Paths[fi.Path]
                if !ok || fld.Embedded {
                        flds.Paths[fi.Path] = fi
                        if fi.Name != "" && !fi.Embedded {
                                flds.Names[fi.Path] = fi
                        }
                }
        }

        return flds
}

package sqlx

import (
        "context"
        "database/sql"
        "database/sql/driver"
        "errors"
        "fmt"
        "os"
        "path/filepath"
        "reflect"
        "strings"
        "sync"

        "github.com/vinovest/sqlx/reflectx"
)

// ErrMultiRows is returned by functions which are expected to work with result sets
// that only contain a single row but multiple rows were returned.
// This typically indicates an issue with the query such as a missing join criteria or
// limit condition or the use of Get(...) when Select(...) was intended.
var ErrMultiRows = errors.New("sql: multiple rows returned")

// Although the NameMapper is convenient, in practice it should not
// be relied on except for application code.  If you are writing a library
// that uses sqlx, you should be aware that the name mappings you expect
// can be overridden by your user's application.

// NameMapper is used to map column names to struct field names.  By default,
// it uses strings.ToLower to lowercase struct field names.  It can be set
// to whatever you want, but it is encouraged to be set before sqlx is used
// as name-to-field mappings are cached after first use on a type.
var NameMapper = strings.ToLower
var origMapper = reflect.ValueOf(NameMapper)

// Rather than creating on init, this is created when necessary so that
// importers have time to customize the NameMapper.
var mpr *reflectx.Mapper

// mprMu protects mpr.
var mprMu sync.Mutex

// mapper returns a valid mapper using the configured NameMapper func.
func mapper() *reflectx.Mapper {
        mprMu.Lock()
        defer mprMu.Unlock()

        if mpr == nil {
                mpr = reflectx.NewMapperFunc("db", NameMapper)
        } else if origMapper != reflect.ValueOf(NameMapper) {
                // if NameMapper has changed, create a new mapper
                mpr = reflectx.NewMapperFunc("db", NameMapper)
                origMapper = reflect.ValueOf(NameMapper)
        }
        return mpr
}

// isScannable takes the reflect.Type and the actual dest value and returns
// whether or not it's Scannable.  Something is scannable if:
//   - it is not a struct
//   - it implements sql.Scanner
//   - it has no exported fields
func isScannable(t reflect.Type) bool {
        if reflect.PointerTo(t).Implements(_scannerInterface) {
                return true
        }
        if t.Kind() != reflect.Struct {
                return true
        }

        // it's not important that we use the right mapper for this particular object,
        // we're only concerned on how many exported fields this struct has
        return len(mapper().TypeMap(t).Index) == 0
}

// ColScanner is an interface used by MapScan and SliceScan
type ColScanner interface {
        Columns() ([]string, error)
        Scan(dest ...interface{}) error
        Err() error
}

// Queryer is an interface used by Get and Select
type Queryer interface {
        Query(query string, args ...interface{}) (*sql.Rows, error)
        Queryx(query string, args ...interface{}) (*Rows, error)
        QueryRowx(query string, args ...interface{}) *Row
}

// Execer is an interface used by MustExec and LoadFile
type Execer interface {
        Exec(query string, args ...interface{}) (sql.Result, error)
}

// Binder is an interface for something which can bind queries (Tx, DB)
type binder interface {
        DriverName() string
        Rebind(string) string
        BindNamed(string, interface{}) (string, []interface{}, error)
}

// Ext is a union interface which can bind, query, and exec, used by
// NamedQuery and NamedExec.
type Ext interface {
        binder
        Queryer
        Execer
}

// Preparer is an interface used by Preparex.
type Preparer interface {
        Prepare(query string) (*sql.Stmt, error)
}

// determine if any of our extensions are unsafe
func isUnsafe(i interface{}) bool {
        switch v := i.(type) {
        case Row:
                return v.unsafe
        case *Row:
                return v.unsafe
        case Rows:
                return v.unsafe
        case *Rows:
                return v.unsafe
        case NamedStmt:
                return v.Stmt.unsafe
        case *NamedStmt:
                return v.Stmt.unsafe
        case Stmt:
                return v.unsafe
        case *Stmt:
                return v.unsafe
        case qStmt:
                return v.unsafe
        case *qStmt:
                return v.unsafe
        case DB:
                return v.unsafe
        case *DB:
                return v.unsafe
        case Tx:
                return v.unsafe
        case *Tx:
                return v.unsafe
        case sql.Rows, *sql.Rows:
                return false
        default:
                return false
        }
}

func mapperFor(i interface{}) *reflectx.Mapper {
        switch i := i.(type) {
        case DB:
                return i.Mapper
        case *DB:
                return i.Mapper
        case Tx:
                return i.Mapper
        case *Tx:
                return i.Mapper
        default:
                return mapper()
        }
}

var _scannerInterface = reflect.TypeOf((*sql.Scanner)(nil)).Elem()

//lint:ignore U1000 ignoring this for now
var _valuerInterface = reflect.TypeOf((*driver.Valuer)(nil)).Elem()

// Row is a reimplementation of sql.Row in order to gain access to the underlying
// sql.Rows.Columns() data, necessary for StructScan.
type Row struct {
        err    error
        unsafe bool
        rows   *sql.Rows
        Mapper *reflectx.Mapper
}

// Scan is a fixed implementation of sql.Row.Scan, which does not discard the
// underlying error from the internal rows object if it exists.
// Returns ErrMultiRows if the result set contains more than one row.
func (r *Row) Scan(dest ...interface{}) error {
        if r.err != nil {
                return r.err
        }

        // TODO(bradfitz): for now we need to defensively clone all
        // []byte that the driver returned (not permitting
        // *RawBytes in Rows.Scan), since we're about to close
        // the Rows in our defer, when we return from this function.
        // the contract with the driver.Next(...) interface is that it
        // can return slices into read-only temporary memory that's
        // only valid until the next Scan/Close.  But the TODO is that
        // for a lot of drivers, this copy will be unnecessary.  We
        // should provide an optional interface for drivers to
        // implement to say, "don't worry, the []bytes that I return
        // from Next will not be modified again." (for instance, if
        // they were obtained from the network anyway) But for now we
        // don't care.
        defer r.rows.Close()
        for _, dp := range dest {
                if _, ok := dp.(*sql.RawBytes); ok {
                        return errors.New("sql: RawBytes isn't allowed on Row.Scan")
                }
        }

        if !r.rows.Next() {
                if err := r.rows.Err(); err != nil {
                        return err
                }
                return sql.ErrNoRows
        }
        if err := r.rows.Scan(dest...); err != nil {
                return err
        }

        if r.rows.Next() {
                return ErrMultiRows
        } else if err := r.rows.Err(); err != nil {
                return err
        }

        // Make sure the query can be processed to completion with no errors.
        if err := r.rows.Close(); err != nil {
                return err
        }
        return nil
}

// Columns returns the underlying sql.Rows.Columns(), or the deferred error usually
// returned by Row.Scan()
func (r *Row) Columns() ([]string, error) {
        if r.err != nil {
                return []string{}, r.err
        }
        return r.rows.Columns()
}

// ColumnTypes returns the underlying sql.Rows.ColumnTypes(), or the deferred error
func (r *Row) ColumnTypes() ([]*sql.ColumnType, error) {
        if r.err != nil {
                return []*sql.ColumnType{}, r.err
        }
        return r.rows.ColumnTypes()
}

// Err returns the error encountered while scanning.
func (r *Row) Err() error {
        return r.err
}

// Queryable includes all methods shared by sqlx.DB and sqlx.Tx, allowing
// either type to be used interchangeably.
type Queryable interface {
        Ext
        ExecerContext
        PreparerContext
        QueryerContext
        Preparer

        GetContext(context.Context, interface{}, string, ...interface{}) error
        SelectContext(context.Context, interface{}, string, ...interface{}) error
        Get(interface{}, string, ...interface{}) error
        MustExecContext(context.Context, string, ...interface{}) sql.Result
        PreparexContext(context.Context, string) (*Stmt, error)
        QueryRowContext(context.Context, string, ...interface{}) *sql.Row
        Select(interface{}, string, ...interface{}) error
        QueryRow(string, ...interface{}) *sql.Row
        PrepareNamedContext(context.Context, string) (*NamedStmt, error)
        PrepareNamed(string) (*NamedStmt, error)
        Preparex(string) (*Stmt, error)
        NamedExec(string, interface{}) (sql.Result, error)
        NamedExecContext(context.Context, string, interface{}) (sql.Result, error)
        MustExec(string, ...interface{}) sql.Result
        NamedQuery(string, interface{}) (*Rows, error)
}

var _ Queryable = (*DB)(nil)
var _ Queryable = (*Tx)(nil)

// DB is a wrapper around sql.DB which keeps track of the driverName upon Open,
// used mostly to automatically bind named queries using the right bindvars.
type DB struct {
        *sql.DB
        driverName string
        unsafe     bool
        Mapper     *reflectx.Mapper
}

// NewDb returns a new sqlx DB wrapper for a pre-existing *sql.DB.  The
// driverName of the original database is required for named query support.
//
//lint:ignore ST1003 changing this would break the package interface.
func NewDb(db *sql.DB, driverName string) *DB {
        return &DB{DB: db, driverName: driverName, Mapper: mapper()}
}

// DriverName returns the driverName passed to the Open function for this DB.
func (db *DB) DriverName() string {
        return db.driverName
}

// Open is the same as sql.Open, but returns an *sqlx.DB instead.
func Open(driverName, dataSourceName string) (*DB, error) {
        db, err := sql.Open(driverName, dataSourceName)
        if err != nil {
                return nil, err
        }
        return &DB{DB: db, driverName: driverName, Mapper: mapper()}, err
}

// MustOpen is the same as sql.Open, but returns an *sqlx.DB instead and panics on error.
func MustOpen(driverName, dataSourceName string) *DB {
        db, err := Open(driverName, dataSourceName)
        if err != nil {
                panic(err)
        }
        return db
}

// MapperFunc sets a new mapper for this db using the default sqlx struct tag
// and the provided mapper function.
func (db *DB) MapperFunc(mf func(string) string) {
        db.Mapper = reflectx.NewMapperFunc("db", mf)
}

// Rebind transforms a query from QUESTION to the DB driver's bindvar type.
func (db *DB) Rebind(query string) string {
        return Rebind(BindType(db.driverName), query)
}

// Unsafe returns a version of DB which will silently succeed to scan when
// columns in the SQL result have no fields in the destination struct.
// sqlx.Stmt and sqlx.Tx which are created from this DB will inherit its
// safety behavior.
func (db *DB) Unsafe() *DB {
        return &DB{DB: db.DB, driverName: db.driverName, unsafe: true, Mapper: db.Mapper}
}

// BindNamed binds a query using the DB driver's bindvar type.
func (db *DB) BindNamed(query string, arg interface{}) (string, []interface{}, error) {
        return bindNamedMapper(BindType(db.driverName), query, arg, db.Mapper)
}

// NamedQuery using this DB.
// Any named placeholder parameters are replaced with fields from arg.
func (db *DB) NamedQuery(query string, arg interface{}) (*Rows, error) {
        return NamedQuery(db, query, arg)
}

// NamedExec using this DB.
// Any named placeholder parameters are replaced with fields from arg.
func (db *DB) NamedExec(query string, arg interface{}) (sql.Result, error) {
        return NamedExec(db, query, arg)
}

// Select using this DB.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) Select(dest interface{}, query string, args ...interface{}) error {
        return Select(db, dest, query, args...)
}

// Get using this DB.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty or contains more than one row.
func (db *DB) Get(dest interface{}, query string, args ...interface{}) error {
        return Get(db, dest, query, args...)
}

// MustBegin starts a transaction, and panics on error.  Returns an *sqlx.Tx instead
// of an *sql.Tx.
func (db *DB) MustBegin() *Tx {
        tx, err := db.Beginx()
        if err != nil {
                panic(err)
        }
        return tx
}

// Beginx begins a transaction and returns an *sqlx.Tx instead of an *sql.Tx.
func (db *DB) Beginx() (*Tx, error) {
        tx, err := db.DB.Begin()
        if err != nil {
                return nil, err
        }
        return &Tx{Tx: tx, driverName: db.driverName, unsafe: db.unsafe, Mapper: db.Mapper}, err
}

// Queryx queries the database and returns an *sqlx.Rows.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) Queryx(query string, args ...interface{}) (*Rows, error) {
        r, err := db.DB.Query(query, args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: db.unsafe, Mapper: db.Mapper}, err
}

// QueryRowx queries the database and returns an *sqlx.Row.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) QueryRowx(query string, args ...interface{}) *Row {
        rows, err := db.DB.Query(query, args...)
        return &Row{rows: rows, err: err, unsafe: db.unsafe, Mapper: db.Mapper}
}

// MustExec (panic) runs MustExec using this database.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) MustExec(query string, args ...interface{}) sql.Result {
        return MustExec(db, query, args...)
}

// Preparex returns an sqlx.Stmt instead of a sql.Stmt
func (db *DB) Preparex(query string) (*Stmt, error) {
        return Preparex(db, query)
}

// PrepareNamed returns an sqlx.NamedStmt
func (db *DB) PrepareNamed(query string) (*NamedStmt, error) {
        return prepareNamed(db, query)
}

// Conn is a wrapper around sql.Conn with extra functionality
type Conn struct {
        *sql.Conn
        driverName string
        unsafe     bool
        Mapper     *reflectx.Mapper
}

// Tx is an sqlx wrapper around sql.Tx with extra functionality
type Tx struct {
        *sql.Tx
        driverName string
        unsafe     bool
        Mapper     *reflectx.Mapper
}

// DriverName returns the driverName used by the DB which began this transaction.
func (tx *Tx) DriverName() string {
        return tx.driverName
}

// Rebind a query within a transaction's bindvar type.
func (tx *Tx) Rebind(query string) string {
        return Rebind(BindType(tx.driverName), query)
}

// Unsafe returns a version of Tx which will silently succeed to scan when
// columns in the SQL result have no fields in the destination struct.
func (tx *Tx) Unsafe() *Tx {
        return &Tx{Tx: tx.Tx, driverName: tx.driverName, unsafe: true, Mapper: tx.Mapper}
}

// BindNamed binds a query within a transaction's bindvar type.
func (tx *Tx) BindNamed(query string, arg interface{}) (string, []interface{}, error) {
        return bindNamedMapper(BindType(tx.driverName), query, arg, tx.Mapper)
}

// NamedQuery within a transaction.
// Any named placeholder parameters are replaced with fields from arg.
func (tx *Tx) NamedQuery(query string, arg interface{}) (*Rows, error) {
        return NamedQuery(tx, query, arg)
}

// NamedExec a named query within a transaction.
// Any named placeholder parameters are replaced with fields from arg.
func (tx *Tx) NamedExec(query string, arg interface{}) (sql.Result, error) {
        return NamedExec(tx, query, arg)
}

// Select within a transaction.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) Select(dest interface{}, query string, args ...interface{}) error {
        return Select(tx, dest, query, args...)
}

// Queryx within a transaction.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) Queryx(query string, args ...interface{}) (*Rows, error) {
        r, err := tx.Tx.Query(query, args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: tx.unsafe, Mapper: tx.Mapper}, err
}

// QueryRowx within a transaction.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) QueryRowx(query string, args ...interface{}) *Row {
        rows, err := tx.Tx.Query(query, args...)
        return &Row{rows: rows, err: err, unsafe: tx.unsafe, Mapper: tx.Mapper}
}

// Get within a transaction.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty or contains more than one row.
func (tx *Tx) Get(dest interface{}, query string, args ...interface{}) error {
        return Get(tx, dest, query, args...)
}

// MustExec runs MustExec within a transaction.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) MustExec(query string, args ...interface{}) sql.Result {
        return MustExec(tx, query, args...)
}

// Preparex  a statement within a transaction.
func (tx *Tx) Preparex(query string) (*Stmt, error) {
        return Preparex(tx, query)
}

// Stmtx returns a version of the prepared statement which runs within a transaction.  Provided
// stmt can be either *sql.Stmt or *sqlx.Stmt.
func (tx *Tx) Stmtx(stmt interface{}) *Stmt {
        var s *sql.Stmt
        switch v := stmt.(type) {
        case Stmt:
                s = v.Stmt
        case *Stmt:
                s = v.Stmt
        case *sql.Stmt:
                s = v
        default:
                panic(fmt.Sprintf("non-statement type %v passed to Stmtx", reflect.ValueOf(stmt).Type()))
        }
        return &Stmt{Stmt: tx.Stmt(s), Mapper: tx.Mapper}
}

// NamedStmt returns a version of the prepared statement which runs within a transaction.
func (tx *Tx) NamedStmt(stmt *NamedStmt) *NamedStmt {
        return &NamedStmt{
                QueryString: stmt.QueryString,
                Params:      stmt.Params,
                Stmt:        tx.Stmtx(stmt.Stmt),
        }
}

// PrepareNamed returns an sqlx.NamedStmt
func (tx *Tx) PrepareNamed(query string) (*NamedStmt, error) {
        return prepareNamed(tx, query)
}

// Stmt is an sqlx wrapper around sql.Stmt with extra functionality
type Stmt struct {
        *sql.Stmt
        unsafe bool
        Mapper *reflectx.Mapper
}

// Unsafe returns a version of Stmt which will silently succeed to scan when
// columns in the SQL result have no fields in the destination struct.
func (s *Stmt) Unsafe() *Stmt {
        return &Stmt{Stmt: s.Stmt, unsafe: true, Mapper: s.Mapper}
}

// Select using the prepared statement.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) Select(dest interface{}, args ...interface{}) error {
        return Select(&qStmt{s}, dest, "", args...)
}

// Get using the prepared statement.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty or contains more than one row.
func (s *Stmt) Get(dest interface{}, args ...interface{}) error {
        return Get(&qStmt{s}, dest, "", args...)
}

// MustExec (panic) using this statement.  Note that the query portion of the error
// output will be blank, as Stmt does not expose its query.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) MustExec(args ...interface{}) sql.Result {
        return MustExec(&qStmt{s}, "", args...)
}

// QueryRowx using this statement.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) QueryRowx(args ...interface{}) *Row {
        qs := &qStmt{s}
        return qs.QueryRowx("", args...)
}

// Queryx using this statement.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) Queryx(args ...interface{}) (*Rows, error) {
        qs := &qStmt{s}
        return qs.Queryx("", args...)
}

// qStmt is an unexposed wrapper which lets you use a Stmt as a Queryer & Execer by
// implementing those interfaces and ignoring the `query` argument.
type qStmt struct{ *Stmt }

func (q *qStmt) Query(query string, args ...interface{}) (*sql.Rows, error) {
        return q.Stmt.Query(args...)
}

func (q *qStmt) Queryx(query string, args ...interface{}) (*Rows, error) {
        r, err := q.Stmt.Query(args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: q.Stmt.unsafe, Mapper: q.Stmt.Mapper}, err
}

func (q *qStmt) QueryRowx(query string, args ...interface{}) *Row {
        rows, err := q.Stmt.Query(args...)
        return &Row{rows: rows, err: err, unsafe: q.Stmt.unsafe, Mapper: q.Stmt.Mapper}
}

func (q *qStmt) Exec(query string, args ...interface{}) (sql.Result, error) {
        return q.Stmt.Exec(args...)
}

// Rows is a wrapper around sql.Rows which caches costly reflect operations
// during a looped StructScan
type Rows struct {
        *sql.Rows
        unsafe bool
        Mapper *reflectx.Mapper
        // these fields cache memory use for a rows during iteration w/ structScan
        started bool
        fields  [][]int
        values  []interface{}
}

// SliceScan using this Rows.
func (r *Rows) SliceScan() ([]interface{}, error) {
        return SliceScan(r)
}

// MapScan using this Rows.
func (r *Rows) MapScan(dest map[string]interface{}) error {
        return MapScan(r, dest)
}

// StructScan is like sql.Rows.Scan, but scans a single Row into a single Struct.
// Use this and iterate over Rows manually when the memory load of Select() might be
// prohibitive.  *Rows.StructScan caches the reflect work of matching up column
// positions to fields to avoid that overhead per scan, which means it is not safe
// to run StructScan on the same Rows instance with different struct types.
func (r *Rows) StructScan(dest interface{}) error {
        v := reflect.ValueOf(dest)

        if v.Kind() != reflect.Ptr {
                return errors.New("must pass a pointer, not a value, to StructScan destination")
        }

        v = v.Elem()

        if !r.started {
                columns, err := r.Columns()
                if err != nil {
                        return err
                }
                m := r.Mapper

                r.fields = m.TraversalsByName(v.Type(), columns)
                // if we are not unsafe and are missing fields, return an error
                if f, err := missingFields(r.fields); err != nil && !r.unsafe {
                        return fmt.Errorf("missing destination name %s in %T", columns[f], dest)
                }
                r.values = make([]interface{}, len(columns))
                r.started = true
        }

        err := fieldsByTraversal(v, r.fields, r.values, true)
        if err != nil {
                return err
        }
        // scan into the struct field pointers and append to our results
        err = r.Scan(r.values...)
        if err != nil {
                return err
        }
        return r.Err()
}

// NextResultSet moves to the next resultset if available and resets the field cache.
func (r *Rows) NextResultSet() bool {
        if !r.Rows.NextResultSet() {
                return false
        }
        // reset fields cache
        r.started = false
        return true
}

// Connect to a database and verify with a ping.
func Connect(driverName, dataSourceName string) (*DB, error) {
        db, err := Open(driverName, dataSourceName)
        if err != nil {
                return nil, err
        }
        err = db.Ping()
        if err != nil {
                db.Close()
                return nil, err
        }
        return db, nil
}

// MustConnect connects to a database and panics on error.
func MustConnect(driverName, dataSourceName string) *DB {
        db, err := Connect(driverName, dataSourceName)
        if err != nil {
                panic(err)
        }
        return db
}

// Preparex prepares a statement.
func Preparex(p Preparer, query string) (*Stmt, error) {
        s, err := p.Prepare(query)
        if err != nil {
                return nil, err
        }
        return &Stmt{Stmt: s, unsafe: isUnsafe(p), Mapper: mapperFor(p)}, err
}

// Select executes a query using the provided Queryer, and StructScans each row
// into dest, which must be a slice.  If the slice elements are scannable, then
// the result set must have only one column.  Otherwise, StructScan is used.
// The *sql.Rows are closed automatically.
// Any placeholder parameters are replaced with supplied args.
func Select(q Queryer, dest interface{}, query string, args ...interface{}) error {
        rows, err := q.Queryx(query, args...)
        if err != nil {
                return err
        }
        // if something happens here, we want to make sure the rows are Closed
        defer rows.Close()
        return scanAll(rows, dest, false)
}

// Get does a QueryRow using the provided Queryer, and scans the resulting row
// to dest.  If dest is scannable, the result must only have one column.  Otherwise,
// StructScan is used.  Get will return sql.ErrNoRows like row.Scan would.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty or contains more than one row.
func Get(q Queryer, dest interface{}, query string, args ...interface{}) error {
        r := q.QueryRowx(query, args...)
        return r.scanAny(dest, false)
}

// LoadFile exec's every statement in a file (as a single call to Exec).
// LoadFile may return a nil *sql.Result if errors are encountered locating or
// reading the file at path.  LoadFile reads the entire file into memory, so it
// is not suitable for loading large data dumps, but can be useful for initializing
// schemas or loading indexes.
//
// FIXME: this does not really work with multi-statement files for mattn/go-sqlite3
// or the go-mysql-driver/mysql drivers;  pq seems to be an exception here.  Detecting
// this by requiring something with DriverName() and then attempting to split the
// queries will be difficult to get right, and its current driver-specific behavior
// is deemed at least not complex in its incorrectness.
func LoadFile(e Execer, path string) (*sql.Result, error) {
        realpath, err := filepath.Abs(path)
        if err != nil {
                return nil, err
        }
        contents, err := os.ReadFile(realpath)
        if err != nil {
                return nil, err
        }
        res, err := e.Exec(string(contents))
        return &res, err
}

// MustExec execs the query using e and panics if there was an error.
// Any placeholder parameters are replaced with supplied args.
func MustExec(e Execer, query string, args ...interface{}) sql.Result {
        res, err := e.Exec(query, args...)
        if err != nil {
                panic(err)
        }
        return res
}

// SliceScan using this Rows.
func (r *Row) SliceScan() ([]interface{}, error) {
        return SliceScan(r)
}

// MapScan using this Rows.
func (r *Row) MapScan(dest map[string]interface{}) error {
        return MapScan(r, dest)
}

func (r *Row) scanAny(dest interface{}, structOnly bool) error {
        if r.err != nil {
                return r.err
        }
        if r.rows == nil {
                r.err = sql.ErrNoRows
                return r.err
        }
        defer r.rows.Close()

        v := reflect.ValueOf(dest)
        if v.Kind() != reflect.Ptr {
                return errors.New("must pass a pointer, not a value, to StructScan destination")
        }
        if v.IsNil() {
                return errors.New("nil pointer passed to StructScan destination")
        }

        base := reflectx.Deref(v.Type())
        scannable := isScannable(base)

        if structOnly && scannable {
                return structOnlyError(base)
        }

        columns, err := r.Columns()
        if err != nil {
                return err
        }

        if scannable && len(columns) > 1 {
                return fmt.Errorf("scannable dest type %s with >1 columns (%d) in result", base.Kind(), len(columns))
        }

        if scannable {
                return r.Scan(dest)
        }

        m := r.Mapper

        fields := m.TraversalsByName(v.Type(), columns)
        // if we are not unsafe and are missing fields, return an error
        if f, err := missingFields(fields); err != nil && !r.unsafe {
                return fmt.Errorf("missing destination name %s in %T", columns[f], dest)
        }
        values := make([]interface{}, len(columns))

        err = fieldsByTraversal(v, fields, values, true)
        if err != nil {
                return err
        }
        // scan into the struct field pointers and append to our results
        return r.Scan(values...)
}

// StructScan a single Row into dest.
func (r *Row) StructScan(dest interface{}) error {
        return r.scanAny(dest, true)
}

// SliceScan a row, returning a []interface{} with values similar to MapScan.
// This function is primarily intended for use where the number of columns
// is not known.  Because you can pass an []interface{} directly to Scan,
// it's recommended that you do that as it will not have to allocate new
// slices per row.
func SliceScan(r ColScanner) ([]interface{}, error) {
        // ignore r.started, since we needn't use reflect for anything.
        columns, err := r.Columns()
        if err != nil {
                return []interface{}{}, err
        }

        values := make([]interface{}, len(columns))
        for i := range values {
                values[i] = new(interface{})
        }

        err = r.Scan(values...)

        if err != nil {
                return values, err
        }

        for i := range columns {
                values[i] = *(values[i].(*interface{}))
        }

        return values, r.Err()
}

// MapScan scans a single Row into the dest map[string]interface{}.
// Use this to get results for SQL that might not be under your control
// (for instance, if you're building an interface for an SQL server that
// executes SQL from input).  Please do not use this as a primary interface!
// This will modify the map sent to it in place, so reuse the same map with
// care.  Columns which occur more than once in the result will overwrite
// each other!
func MapScan(r ColScanner, dest map[string]interface{}) error {
        // ignore r.started, since we needn't use reflect for anything.
        columns, err := r.Columns()
        if err != nil {
                return err
        }

        values := make([]interface{}, len(columns))
        for i := range values {
                values[i] = new(interface{})
        }

        err = r.Scan(values...)
        if err != nil {
                return err
        }

        for i, column := range columns {
                dest[column] = *(values[i].(*interface{}))
        }

        return r.Err()
}

type rowsi interface {
        Close() error
        Columns() ([]string, error)
        Err() error
        Next() bool
        Scan(...interface{}) error
}

// structOnlyError returns an error appropriate for type when a non-scannable
// struct is expected but something else is given
func structOnlyError(t reflect.Type) error {
        isStruct := t.Kind() == reflect.Struct
        isScanner := reflect.PointerTo(t).Implements(_scannerInterface)
        if !isStruct {
                return fmt.Errorf("expected %s but got %s", reflect.Struct, t.Kind())
        }
        if isScanner {
                return fmt.Errorf("structscan expects a struct dest but the provided struct type %s implements scanner", t.Name())
        }
        return fmt.Errorf("expected a struct, but struct %s has no exported fields", t.Name())
}

// scanAll scans all rows into a destination, which must be a slice of any
// type.  It resets the slice length to zero before appending each element to
// the slice.  If the destination slice type is a Struct, then StructScan will
// be used on each row.  If the destination is some other kind of base type,
// then each row must only have one column which can scan into that type.  This
// allows you to do something like:
//
//        rows, _ := db.Query("select id from people;")
//        var ids []int
//        scanAll(rows, &ids, false)
//
// and ids will be a list of the id results.  I realize that this is a desirable
// interface to expose to users, but for now it will only be exposed via changes
// to `Get` and `Select`.  The reason that this has been implemented like this is
// this is the only way to not duplicate reflect work in the new API while
// maintaining backwards compatibility.
func scanAll(rows rowsi, dest interface{}, structOnly bool) error {
        var v, vp reflect.Value

        value := reflect.ValueOf(dest)

        // json.Unmarshal returns errors for these
        if value.Kind() != reflect.Ptr {
                return errors.New("must pass a pointer, not a value, to StructScan destination")
        }
        if value.IsNil() {
                return errors.New("nil pointer passed to StructScan destination")
        }
        direct := reflect.Indirect(value)

        slice, err := baseType(value.Type(), reflect.Slice)
        if err != nil {
                return err
        }
        direct.SetLen(0)

        isPtr := slice.Elem().Kind() == reflect.Ptr
        base := reflectx.Deref(slice.Elem())
        scannable := isScannable(base)

        if structOnly && scannable {
                return structOnlyError(base)
        }

        columns, err := rows.Columns()
        if err != nil {
                return err
        }

        // if it's a base type make sure it only has 1 column;  if not return an error
        if scannable && len(columns) > 1 {
                return fmt.Errorf("non-struct dest type %s with >1 columns (%d)", base.Kind(), len(columns))
        }

        if !scannable {
                var values []interface{}
                var m *reflectx.Mapper

                switch rows := rows.(type) {
                case *Rows:
                        m = rows.Mapper
                default:
                        m = mapper()
                }

                fields := m.TraversalsByName(base, columns)
                // if we are not unsafe and are missing fields, return an error
                if f, err := missingFields(fields); err != nil && !isUnsafe(rows) {
                        return fmt.Errorf("missing destination name %s in %T", columns[f], dest)
                }
                values = make([]interface{}, len(columns))

                for rows.Next() {
                        // create a new struct type (which returns PtrTo) and indirect it
                        vp = reflect.New(base)
                        v = reflect.Indirect(vp)

                        err = fieldsByTraversal(v, fields, values, true)
                        if err != nil {
                                return err
                        }

                        // scan into the struct field pointers and append to our results
                        err = rows.Scan(values...)
                        if err != nil {
                                return err
                        }

                        if isPtr {
                                direct.Set(reflect.Append(direct, vp))
                        } else {
                                direct.Set(reflect.Append(direct, v))
                        }
                }
        } else {
                for rows.Next() {
                        vp = reflect.New(base)
                        err = rows.Scan(vp.Interface())
                        if err != nil {
                                return err
                        }
                        // append
                        if isPtr {
                                direct.Set(reflect.Append(direct, vp))
                        } else {
                                direct.Set(reflect.Append(direct, reflect.Indirect(vp)))
                        }
                }
        }

        return rows.Err()
}

// FIXME: StructScan was the very first bit of API in sqlx, and now unfortunately
// it doesn't really feel like it's named properly.  There is an incongruency
// between this and the way that StructScan (which might better be ScanStruct
// anyway) works on a rows object.

// StructScan all rows from an sql.Rows or an sqlx.Rows into the dest slice.
// StructScan will scan in the entire rows result, so if you do not want to
// allocate structs for the entire result, use Queryx and see sqlx.Rows.StructScan.
// If rows is sqlx.Rows, it will use its mapper, otherwise it will use the default.
func StructScan(rows rowsi, dest interface{}) error {
        return scanAll(rows, dest, true)

}

// reflect helpers

func baseType(t reflect.Type, expected reflect.Kind) (reflect.Type, error) {
        t = reflectx.Deref(t)
        if t.Kind() != expected {
                return nil, fmt.Errorf("expected %s but got %s", expected, t.Kind())
        }
        return t, nil
}

// fieldsByName fills a values interface with fields from the passed value based
// on the traversals in int.  If ptrs is true, return addresses instead of values.
// We write this instead of using FieldsByName to save allocations and map lookups
// when iterating over many rows.  Empty traversals will get an interface pointer.
// Because of the necessity of requesting ptrs or values, it's considered a bit too
// specialized for inclusion in reflectx itself.
func fieldsByTraversal(v reflect.Value, traversals [][]int, values []interface{}, ptrs bool) error {
        v = reflect.Indirect(v)
        if v.Kind() != reflect.Struct {
                return errors.New("argument not a struct")
        }

        for i, traversal := range traversals {
                if len(traversal) == 0 {
                        values[i] = new(interface{})
                        continue
                }
                f := reflectx.FieldByIndexes(v, traversal)
                if ptrs {
                        values[i] = f.Addr().Interface()
                } else {
                        values[i] = f.Interface()
                }
        }
        return nil
}

func missingFields(transversals [][]int) (field int, err error) {
        for i, t := range transversals {
                if len(t) == 0 {
                        return i, errors.New("missing field")
                }
        }
        return 0, nil
}

package sqlx

import (
        "context"
        "database/sql"
        "fmt"
        "os"
        "path/filepath"
        "reflect"
)

// ConnectContext to a database and verify with a ping.
func ConnectContext(ctx context.Context, driverName, dataSourceName string) (*DB, error) {
        db, err := Open(driverName, dataSourceName)
        if err != nil {
                return db, err
        }
        err = db.PingContext(ctx)
        return db, err
}

// QueryerContext is an interface used by GetContext and SelectContext
type QueryerContext interface {
        QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
        QueryxContext(ctx context.Context, query string, args ...interface{}) (*Rows, error)
        QueryRowxContext(ctx context.Context, query string, args ...interface{}) *Row
}

// PreparerContext is an interface used by PreparexContext.
type PreparerContext interface {
        PrepareContext(ctx context.Context, query string) (*sql.Stmt, error)
}

// ExecerContext is an interface used by MustExecContext and LoadFileContext
type ExecerContext interface {
        ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
}

// ExtContext is a union interface which can bind, query, and exec, with Context
// used by NamedQueryContext and NamedExecContext.
type ExtContext interface {
        binder
        QueryerContext
        ExecerContext
}

// SelectContext executes a query using the provided Queryer, and StructScans
// each row into dest, which must be a slice.  If the slice elements are
// scannable, then the result set must have only one column.  Otherwise,
// StructScan is used. The *sql.Rows are closed automatically.
// Any placeholder parameters are replaced with supplied args.
func SelectContext(ctx context.Context, q QueryerContext, dest interface{}, query string, args ...interface{}) error {
        rows, err := q.QueryxContext(ctx, query, args...)
        if err != nil {
                return err
        }
        // if something happens here, we want to make sure the rows are Closed
        defer rows.Close()
        return scanAll(rows, dest, false)
}

// PreparexContext prepares a statement.
//
// The provided context is used for the preparation of the statement, not for
// the execution of the statement.
func PreparexContext(ctx context.Context, p PreparerContext, query string) (*Stmt, error) {
        s, err := p.PrepareContext(ctx, query)
        if err != nil {
                return nil, err
        }
        return &Stmt{Stmt: s, unsafe: isUnsafe(p), Mapper: mapperFor(p)}, err
}

// GetContext does a QueryRow using the provided Queryer, and scans the
// resulting row to dest.  If dest is scannable, the result must only have one
// column. Otherwise, StructScan is used.  Get will return sql.ErrNoRows like
// row.Scan would. Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty.
func GetContext(ctx context.Context, q QueryerContext, dest interface{}, query string, args ...interface{}) error {
        r := q.QueryRowxContext(ctx, query, args...)
        return r.scanAny(dest, false)
}

// LoadFileContext exec's every statement in a file (as a single call to Exec).
// LoadFileContext may return a nil *sql.Result if errors are encountered
// locating or reading the file at path.  LoadFile reads the entire file into
// memory, so it is not suitable for loading large data dumps, but can be useful
// for initializing schemas or loading indexes.
//
// FIXME: this does not really work with multi-statement files for mattn/go-sqlite3
// or the go-mysql-driver/mysql drivers;  pq seems to be an exception here.  Detecting
// this by requiring something with DriverName() and then attempting to split the
// queries will be difficult to get right, and its current driver-specific behavior
// is deemed at least not complex in its incorrectness.
func LoadFileContext(ctx context.Context, e ExecerContext, path string) (*sql.Result, error) {
        realpath, err := filepath.Abs(path)
        if err != nil {
                return nil, err
        }
        contents, err := os.ReadFile(realpath)
        if err != nil {
                return nil, err
        }
        res, err := e.ExecContext(ctx, string(contents))
        return &res, err
}

// MustExecContext execs the query using e and panics if there was an error.
// Any placeholder parameters are replaced with supplied args.
func MustExecContext(ctx context.Context, e ExecerContext, query string, args ...interface{}) sql.Result {
        res, err := e.ExecContext(ctx, query, args...)
        if err != nil {
                panic(err)
        }
        return res
}

// PrepareNamedContext returns an sqlx.NamedStmt
func (db *DB) PrepareNamedContext(ctx context.Context, query string) (*NamedStmt, error) {
        return prepareNamedContext(ctx, db, query)
}

// NamedQueryContext using this DB.
// Any named placeholder parameters are replaced with fields from arg.
func (db *DB) NamedQueryContext(ctx context.Context, query string, arg interface{}) (*Rows, error) {
        return NamedQueryContext(ctx, db, query, arg)
}

// NamedExecContext using this DB.
// Any named placeholder parameters are replaced with fields from arg.
func (db *DB) NamedExecContext(ctx context.Context, query string, arg interface{}) (sql.Result, error) {
        return NamedExecContext(ctx, db, query, arg)
}

// SelectContext using this DB.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) SelectContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
        return SelectContext(ctx, db, dest, query, args...)
}

// GetContext using this DB.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty.
func (db *DB) GetContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
        return GetContext(ctx, db, dest, query, args...)
}

// PreparexContext returns an sqlx.Stmt instead of a sql.Stmt.
//
// The provided context is used for the preparation of the statement, not for
// the execution of the statement.
func (db *DB) PreparexContext(ctx context.Context, query string) (*Stmt, error) {
        return PreparexContext(ctx, db, query)
}

// QueryxContext queries the database and returns an *sqlx.Rows.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) QueryxContext(ctx context.Context, query string, args ...interface{}) (*Rows, error) {
        r, err := db.DB.QueryContext(ctx, query, args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: db.unsafe, Mapper: db.Mapper}, err
}

// QueryRowxContext queries the database and returns an *sqlx.Row.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) QueryRowxContext(ctx context.Context, query string, args ...interface{}) *Row {
        rows, err := db.DB.QueryContext(ctx, query, args...)
        return &Row{rows: rows, err: err, unsafe: db.unsafe, Mapper: db.Mapper}
}

// MustBeginTx starts a transaction, and panics on error.  Returns an *sqlx.Tx instead
// of an *sql.Tx.
//
// The provided context is used until the transaction is committed or rolled
// back. If the context is canceled, the sql package will roll back the
// transaction. Tx.Commit will return an error if the context provided to
// MustBeginContext is canceled.
func (db *DB) MustBeginTx(ctx context.Context, opts *sql.TxOptions) *Tx {
        tx, err := db.BeginTxx(ctx, opts)
        if err != nil {
                panic(err)
        }
        return tx
}

// MustExecContext (panic) runs MustExec using this database.
// Any placeholder parameters are replaced with supplied args.
func (db *DB) MustExecContext(ctx context.Context, query string, args ...interface{}) sql.Result {
        return MustExecContext(ctx, db, query, args...)
}

// BeginTxx begins a transaction and returns an *sqlx.Tx instead of an
// *sql.Tx.
//
// The provided context is used until the transaction is committed or rolled
// back. If the context is canceled, the sql package will roll back the
// transaction. Tx.Commit will return an error if the context provided to
// BeginxContext is canceled.
func (db *DB) BeginTxx(ctx context.Context, opts *sql.TxOptions) (*Tx, error) {
        tx, err := db.DB.BeginTx(ctx, opts)
        if err != nil {
                return nil, err
        }
        return &Tx{Tx: tx, driverName: db.driverName, unsafe: db.unsafe, Mapper: db.Mapper}, err
}

// Connx returns an *sqlx.Conn instead of an *sql.Conn.
func (db *DB) Connx(ctx context.Context) (*Conn, error) {
        conn, err := db.DB.Conn(ctx)
        if err != nil {
                return nil, err
        }

        return &Conn{Conn: conn, driverName: db.driverName, unsafe: db.unsafe, Mapper: db.Mapper}, nil
}

// BeginTxx begins a transaction and returns an *sqlx.Tx instead of an
// *sql.Tx.
//
// The provided context is used until the transaction is committed or rolled
// back. If the context is canceled, the sql package will roll back the
// transaction. Tx.Commit will return an error if the context provided to
// BeginxContext is canceled.
func (c *Conn) BeginTxx(ctx context.Context, opts *sql.TxOptions) (*Tx, error) {
        tx, err := c.Conn.BeginTx(ctx, opts)
        if err != nil {
                return nil, err
        }
        return &Tx{Tx: tx, driverName: c.driverName, unsafe: c.unsafe, Mapper: c.Mapper}, err
}

// SelectContext using this Conn.
// Any placeholder parameters are replaced with supplied args.
func (c *Conn) SelectContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
        return SelectContext(ctx, c, dest, query, args...)
}

// GetContext using this Conn.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty.
func (c *Conn) GetContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
        return GetContext(ctx, c, dest, query, args...)
}

// PreparexContext returns an sqlx.Stmt instead of a sql.Stmt.
//
// The provided context is used for the preparation of the statement, not for
// the execution of the statement.
func (c *Conn) PreparexContext(ctx context.Context, query string) (*Stmt, error) {
        return PreparexContext(ctx, c, query)
}

// QueryxContext queries the database and returns an *sqlx.Rows.
// Any placeholder parameters are replaced with supplied args.
func (c *Conn) QueryxContext(ctx context.Context, query string, args ...interface{}) (*Rows, error) {
        r, err := c.Conn.QueryContext(ctx, query, args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: c.unsafe, Mapper: c.Mapper}, err
}

// QueryRowxContext queries the database and returns an *sqlx.Row.
// Any placeholder parameters are replaced with supplied args.
func (c *Conn) QueryRowxContext(ctx context.Context, query string, args ...interface{}) *Row {
        rows, err := c.Conn.QueryContext(ctx, query, args...)
        return &Row{rows: rows, err: err, unsafe: c.unsafe, Mapper: c.Mapper}
}

// Rebind a query within a Conn's bindvar type.
func (c *Conn) Rebind(query string) string {
        return Rebind(BindType(c.driverName), query)
}

// StmtxContext returns a version of the prepared statement which runs within a
// transaction. Provided stmt can be either *sql.Stmt or *sqlx.Stmt.
func (tx *Tx) StmtxContext(ctx context.Context, stmt interface{}) *Stmt {
        var s *sql.Stmt
        switch v := stmt.(type) {
        case Stmt:
                s = v.Stmt
        case *Stmt:
                s = v.Stmt
        case *sql.Stmt:
                s = v
        default:
                panic(fmt.Sprintf("non-statement type %v passed to Stmtx", reflect.ValueOf(stmt).Type()))
        }
        return &Stmt{Stmt: tx.StmtContext(ctx, s), Mapper: tx.Mapper}
}

// NamedStmtContext returns a version of the prepared statement which runs
// within a transaction.
func (tx *Tx) NamedStmtContext(ctx context.Context, stmt *NamedStmt) *NamedStmt {
        return &NamedStmt{
                QueryString: stmt.QueryString,
                Params:      stmt.Params,
                Stmt:        tx.StmtxContext(ctx, stmt.Stmt),
        }
}

// PreparexContext returns an sqlx.Stmt instead of a sql.Stmt.
//
// The provided context is used for the preparation of the statement, not for
// the execution of the statement.
func (tx *Tx) PreparexContext(ctx context.Context, query string) (*Stmt, error) {
        return PreparexContext(ctx, tx, query)
}

// PrepareNamedContext returns an sqlx.NamedStmt
func (tx *Tx) PrepareNamedContext(ctx context.Context, query string) (*NamedStmt, error) {
        return prepareNamedContext(ctx, tx, query)
}

// MustExecContext runs MustExecContext within a transaction.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) MustExecContext(ctx context.Context, query string, args ...interface{}) sql.Result {
        return MustExecContext(ctx, tx, query, args...)
}

// QueryxContext within a transaction and context.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) QueryxContext(ctx context.Context, query string, args ...interface{}) (*Rows, error) {
        r, err := tx.Tx.QueryContext(ctx, query, args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: tx.unsafe, Mapper: tx.Mapper}, err
}

// SelectContext within a transaction and context.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) SelectContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
        return SelectContext(ctx, tx, dest, query, args...)
}

// GetContext within a transaction and context.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty.
func (tx *Tx) GetContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
        return GetContext(ctx, tx, dest, query, args...)
}

// QueryRowxContext within a transaction and context.
// Any placeholder parameters are replaced with supplied args.
func (tx *Tx) QueryRowxContext(ctx context.Context, query string, args ...interface{}) *Row {
        rows, err := tx.Tx.QueryContext(ctx, query, args...)
        return &Row{rows: rows, err: err, unsafe: tx.unsafe, Mapper: tx.Mapper}
}

// NamedExecContext using this Tx.
// Any named placeholder parameters are replaced with fields from arg.
func (tx *Tx) NamedExecContext(ctx context.Context, query string, arg interface{}) (sql.Result, error) {
        return NamedExecContext(ctx, tx, query, arg)
}

// SelectContext using the prepared statement.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) SelectContext(ctx context.Context, dest interface{}, args ...interface{}) error {
        return SelectContext(ctx, &qStmt{s}, dest, "", args...)
}

// GetContext using the prepared statement.
// Any placeholder parameters are replaced with supplied args.
// An error is returned if the result set is empty.
func (s *Stmt) GetContext(ctx context.Context, dest interface{}, args ...interface{}) error {
        return GetContext(ctx, &qStmt{s}, dest, "", args...)
}

// MustExecContext (panic) using this statement.  Note that the query portion of
// the error output will be blank, as Stmt does not expose its query.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) MustExecContext(ctx context.Context, args ...interface{}) sql.Result {
        return MustExecContext(ctx, &qStmt{s}, "", args...)
}

// QueryRowxContext using this statement.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) QueryRowxContext(ctx context.Context, args ...interface{}) *Row {
        qs := &qStmt{s}
        return qs.QueryRowxContext(ctx, "", args...)
}

// QueryxContext using this statement.
// Any placeholder parameters are replaced with supplied args.
func (s *Stmt) QueryxContext(ctx context.Context, args ...interface{}) (*Rows, error) {
        qs := &qStmt{s}
        return qs.QueryxContext(ctx, "", args...)
}

func (q *qStmt) QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error) {
        return q.Stmt.QueryContext(ctx, args...)
}

func (q *qStmt) QueryxContext(ctx context.Context, query string, args ...interface{}) (*Rows, error) {
        r, err := q.Stmt.QueryContext(ctx, args...)
        if err != nil {
                return nil, err
        }
        return &Rows{Rows: r, unsafe: q.Stmt.unsafe, Mapper: q.Stmt.Mapper}, err
}

func (q *qStmt) QueryRowxContext(ctx context.Context, query string, args ...interface{}) *Row {
        rows, err := q.Stmt.QueryContext(ctx, args...)
        return &Row{rows: rows, err: err, unsafe: q.Stmt.unsafe, Mapper: q.Stmt.Mapper}
}

func (q *qStmt) ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error) {
        return q.Stmt.ExecContext(ctx, args...)
}

package types

import (
        "bytes"
        "compress/gzip"
        "database/sql/driver"
        "encoding/json"
        "errors"
        "io"
)

// GzippedText is a []byte which transparently gzips data being submitted to
// a database and ungzips data being Scanned from a database.
type GzippedText []byte

// Value implements the driver.Valuer interface, gzipping the raw value of
// this GzippedText.
func (g GzippedText) Value() (driver.Value, error) {
        b := make([]byte, 0, len(g))
        buf := bytes.NewBuffer(b)
        w := gzip.NewWriter(buf)
        w.Write(g)
        w.Close()
        return buf.Bytes(), nil

}

// Scan implements the sql.Scanner interface, ungzipping the value coming off
// the wire and storing the raw result in the GzippedText.
func (g *GzippedText) Scan(src interface{}) error {
        var source []byte
        switch src := src.(type) {
        case string:
                source = []byte(src)
        case []byte:
                source = src
        default:
                //lint:ignore ST1005 changing this could break consumers of this package
                return errors.New("Incompatible type for GzippedText")
        }
        reader, err := gzip.NewReader(bytes.NewReader(source))
        if err != nil {
                return err
        }
        defer reader.Close()
        b, err := io.ReadAll(reader)
        if err != nil {
                return err
        }
        *g = GzippedText(b)
        return nil
}

// JSONText is a json.RawMessage, which is a []byte underneath.
// Value() validates the json format in the source, and returns an error if
// the json is not valid.  Scan does no validation.  JSONText additionally
// implements `Unmarshal`, which unmarshals the json within to an interface{}
type JSONText json.RawMessage

var emptyJSON = JSONText("{}")

// MarshalJSON returns the *j as the JSON encoding of j.
func (j JSONText) MarshalJSON() ([]byte, error) {
        if len(j) == 0 {
                return emptyJSON, nil
        }
        return j, nil
}

// UnmarshalJSON sets *j to a copy of data
func (j *JSONText) UnmarshalJSON(data []byte) error {
        if j == nil {
                return errors.New("JSONText: UnmarshalJSON on nil pointer")
        }
        *j = append((*j)[0:0], data...)
        return nil
}

// Value returns j as a value.  This does a validating unmarshal into another
// RawMessage.  If j is invalid json, it returns an error.
func (j JSONText) Value() (driver.Value, error) {
        var m json.RawMessage
        var err = j.Unmarshal(&m)
        if err != nil {
                return []byte{}, err
        }
        return []byte(j), nil
}

// Scan stores the src in *j.  No validation is done.
func (j *JSONText) Scan(src interface{}) error {
        var source []byte
        switch t := src.(type) {
        case string:
                source = []byte(t)
        case []byte:
                if len(t) == 0 {
                        source = emptyJSON
                } else {
                        source = t
                }
        case nil:
                *j = emptyJSON
        default:
                //lint:ignore ST1005 changing this could break consumers of this package
                return errors.New("Incompatible type for JSONText")
        }
        *j = append((*j)[0:0], source...)
        return nil
}

// Unmarshal unmarshal's the json in j to v, as in json.Unmarshal.
func (j *JSONText) Unmarshal(v interface{}) error {
        if len(*j) == 0 {
                *j = emptyJSON
        }
        return json.Unmarshal([]byte(*j), v)
}

// String supports pretty printing for JSONText types.
func (j JSONText) String() string {
        return string(j)
}

// NullJSONText represents a JSONText that may be null.
// NullJSONText implements the scanner interface so
// it can be used as a scan destination, similar to NullString.
type NullJSONText struct {
        JSONText
        Valid bool // Valid is true if JSONText is not NULL
}

// Scan implements the Scanner interface.
func (n *NullJSONText) Scan(value interface{}) error {
        if value == nil {
                n.JSONText, n.Valid = emptyJSON, false
                return nil
        }
        n.Valid = true
        return n.JSONText.Scan(value)
}

// Value implements the driver Valuer interface.
func (n NullJSONText) Value() (driver.Value, error) {
        if !n.Valid {
                return nil, nil
        }
        return n.JSONText.Value()
}

// BitBool is an implementation of a bool for the MySQL type BIT(1).
// This type allows you to avoid wasting an entire byte for MySQL's boolean type TINYINT.
type BitBool bool

// Value implements the driver.Valuer interface,
// and turns the BitBool into a bitfield (BIT(1)) for MySQL storage.
func (b BitBool) Value() (driver.Value, error) {
        if b {
                return []byte{1}, nil
        }
        return []byte{0}, nil
}

// Scan implements the sql.Scanner interface,
// and turns the bitfield incoming from MySQL into a BitBool
func (b *BitBool) Scan(src interface{}) error {
        v, ok := src.([]byte)
        if !ok {
                return errors.New("bad []byte type assertion")
        }
        *b = v[0] == 1
        return nil
}